Wildfires in California, Oregon, Idaho, and Nevada sent smoke over large stretches of the United States in mid-August 2012. Particularly thick smoke collected over Wyoming on August 14, when the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite captured this natural-color image. Smoke filled the skies over most of the state; over the south-central part of the state, it was thick enough to completely hide the land surface below.

Although smoke appeared especially thick over Wyoming, air quality suffered across the United States. The “Smog Blog” at the University of Maryland-Baltimore County reported that smoke plumes stretched from northern California eastward to Nebraska. Plumes also extended over the Upper Midwest and northward into Canada. Over the westernmost United States, smoke mixed with ozone, prompting numerous air-quality alerts, Smog Blog reported.